Humans retrieve the memory of an event in reverse to how they saw it, a report published today has discovered.

Instead of constructing a past memory by building a picture from details of the event, the brain forms an overall 'gist' of what happened first.

It then fills out the story by retrieving more detail.

This process seems to be the opposite of how the brain works when first encountering an event.

The latest findings may give scientists greater insight into the reliability and accuracy of memory and witness accounts of incidents such as crime.

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Humans retrieve the memory of an event in reverse to how they saw it, a report published today has discovered. Instead of constructing a past memory by building a picture from details of the event, the brain forms an overall 'gist' of what happened first. It then fills out the story by retrieving more detail (stock image)

Researchers from the University of Birmingham showed participants specific images and asked to associate each image with a unique word.

They were later given the word and asked to remember the image in as much detail as possible.

Throughout this process, each participant's brain activities were monitored using 128 electrodes attached to the scalp.

The electrodes allowed scientists to look at changes in brain patterns with millisecond precision.

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A decoding algorithm was used to work out the type of images being formed in the brain at different time points.

Juan Linde Domingo, lead author of the study, said: 'Memory is a reconstructive process, biased by personal knowledge and world views.

'But exactly how memories are reconstructed in the brain, step by step, is currently not well understood.'

This process uncovered by researchers seems to be the opposite of how the brain works when first encountering an event. The latest findings may give scientists greater insight into the reliability and accuracy of memory and witness accounts of incidents such as crime (stock image)

The findings from the study are in sharp contrast to how the brain processes images when it first encounters them.

When we initially see a complex object, it's the visual details - patterns and colours - that we perceive first.

Abstract, meaningful information that tells us the nature of the object we're looking at, whether it's a dog, a guitar, or a cup, for example, comes late.

It also suggests that the brain prioritises concepts over details, which has further implications for how memory can change with each process of retrieval.

It is unclear whether the reverse process found is 'hard-wired', and if it is different in more complex cases where more than an image is involved.

It could also have implications for conditions such as Post Traumatic Disorders.

Dr Maria Wimber, senior author of the study, added: 'We were able to show that the participants were retrieving higher-level, abstract information, shortly after they heard the reminder word. It was only later that they retrieved the specific details.'

HOW DO WE LEARN?

The human brain consists of billions of neurons, electrically excitable cells that receive, process, and transmit information through electrical and chemical signals.

These neurons are connected together to form billions of different neural pathways.

Our brain develops a new pathway when we experience something new and each new experience can change our future behaviour.

With repeated experiences, these pathways becomes stronger and with further repetition, can be cemented as a learned skill.

Neuroscientists at the University of California Irvine’s Center were able to prove what they had long suspected when they were able to isolate and observe the actions of the brain while learning a new task in the brains of mice.

They found that, when two neurons frequently interact, they form a bond that allows them to transmit more easily and accurately.

This led to more complete memories and easier recall.

Conversely, when two neurons rarely interacted, the transmission was often incomplete, leading to either a faulty memory or no memory at all.